Modeling and Simulation of Ultrahigh Sensitive AlGaN/AlN/GaN HEMT-Based Hydrogen Gas Detector With Low Detection Limit

Abstract

Presented through this work is a steady state analytical model of the GaN HEMT based gas detector. GaN with high chemical and thermal stability provides promises for detectors in hazardous environments. However, HEMT sensor resolution must be improved to develop high precision gas sensors for automotive and space applications. The proposed model aids in systematical study of the sensor performance and prediction of sensitivities. The linear relation of threshold voltage shift at thermal equilibrium is used in predicting the sensor response. Numerical model for the reaction rates and the electrical dipole at the adsorption sites at the surface and metal/semiconductor interface have been developed and the sensor performance is analyzed for various gas concentrations. The validation of the model has been achieved through surface and interfacial charge adsorption-based gate electrode work function, Schottky barrier, 2DEG and threshold voltage deduction using MATLAB and SILVACO ATLAS TCAD. Further the applicability of gd (channel conductance) as gas sensing metric is also presented. With high ID and gd percentile sensitivities of 118.5% and 92 % for 10 ppm hydrogen concentration. The sensor shows capability for detection in sub-ppm levels by exhibiting a response of 0.043% for 0.01ppm (10 ppb) hydrogen concentration. The detection limit of the sensor (1% sensitivity) presented here is 169 ppb and the device current increases by 34.2 μA for 1ppb hydrogen concentration.

GaN-HEMT on Si as a Robust Visible-Blind UV Detector With High Responsivity

“…AlN spacer used between AlGaN/GaN layers have shown to improve the performance of the HEMTs, in DC, RF and sensing domains [6,14,16,17]. This technology is made use here to get detectors with enhanced.…”

“…ALLIUM nitride electronics has gained huge attention in recent years due to its inherent advantages of the wide band gap material and Two-Dimensional Electron Gas (2DEG) formation when an AlGaN/GaN heterojunction is grown [1,2]. High frequency power electronics, optical and sensing technology are the three main application domains of GaN based devices [3][4][5][6]. Recent years have seen an increased interest in development of UV detectors due to their increased demands in military, civil and space applications [7,8].…”

“…Presented here is a systematic approach towards development of a UV detector where simulation models are developed and used so that the fabrication costs, time, costs and resource overheads can be minimized. Such methods of modeling prior to fabrication have been employed in transistor-based chemical and bio sensor design but has not been used till date in photo detector simulations [6,[12][13][14][15]. This work presents the use of optical module in Silvaco ATLAS TCAD to simulate the device performance as a UV detector followed by fabrication and characterization of the detector along with its fabrication and characterization.…”

Junctionfree Gate Stacked Vertical TFET Hydrogen Sensor at Room Temperature

“…As the hydrogen molecules get adsorbed at the surface of the sensing gate, a work function variation of the sensing gate is initiated based upon the interaction between sensing gate metal and hydrogen molecules, thus hydrogen atoms are generated from the dissociation of hydrogen molecules. The effective variation in metal work function (∆φM) can be expressed in terms of molar concentration and partial pressure of the target gas [18], [29]:…”

“…where 'R' is the gas constant = 8.314 JM −1 K −1 , 'T' is the temperature= 300 K and 'F' is Faraday's constant= 96500 CM −1 respectively. 'P' is the target gas partial pressure taken as 2.5 Pa [29]. The variations in threshold voltage (VTH) and flat-band voltage (VFB) owing to the variation in work function (∆φM), leads to a change in on and off currents given by equation ( 2) [18], [30]:…”